Golf balls are required to ensure flight stability, long flight distance characteristics and must be durable to withstand repeated impact with a golf club head. In addition to these characteristics, other desirable features of the golf ball are good compression, good cut, and shatter resistance. The golf ball should have an elastic modulus providing the capability for storing the energy of deformation and quickly releasing it to regain sphericity after being sharply struck by a golf club head. The golf ball should further provide a good click sound when fairly hit, and should have inherently good balance to thereby provide aerodynamic stability and true roll on a putting green or other surface. Over the years, the preferred material used in manufacturing golf balls has been rubber compositions. The rubber compositions used in golf ball covers are therefore required to have well controlled properties such as bounce impact elasticity, compressive strength and hardness to name but a few. One other consideration to take note of when manufacturing a golf ball is the United States Golf Association's series of rules which govern golf balls.
The United States Golf Association has implemented a series of rules with respect to the physical characteristics and performance properties of golf balls to create a uniform system of play. Included within these series of rules are specific provisions that govern that: (a) the weight of a golf ball shall not be greater than 1.620 ounces (45.93 gm); (b) the diameter of a golf ball shall be not less than 1.680 inches 42.67 mm); (c) the velocity of the golf ball shall not be greater than 250 ft (76.2 m) per second plus a tolerance of 2%; (d) the overall distance that the golf ball will travel shall not be cover an average distance in carry and roll exceeding 280 yards plus a tolerance of 6%. In view of these physical and performance properties, golf ball manufacturers seek to produce golf balls which balance these properties and exhibit superior play.
Golf balls have evolved from their early form which simply consisted of a stuffed cover to golf ball covers formed of either a naturally occurring rubber called balata or gutta percha which comprises a packing material used in the transportation of cargo. While balata is a more desirable material because it is a softer material which has a higher potential to impart high spin and controllability to the golf balls. Unfortunately, balata is a very difficult material to use in the manufacturing process for fabricating the golf balls.
Even more recently, in the late 1960's, a new material for forming golf ball covers was introduced by DuPont under the trade name SURLYN. SURYLN materials are a class of ethylene-methacrylic acid based ionomers. In addition, lately, various companies have investigated using polyurethane as a golf ball cover material.
The golf ball cover material also includes other components which are added to improve various properties of the golf ball. For example, it is a common practice to add a brightener or whitener to the golf ball cover material since most golf ball cover materials, e.g., SURLYN or balata, are not a pure white in color and as even the most novice golfer would know the vast majority of golf balls are distributed and marketed in a white color. The main purpose of enhancing the brighteness or whiteness of the golf ball is to make it aesthetically pleasing. The golf ball cover material may further include filler materials, polymerization initiators, U.V. stabilizers, light stabilizers, antioxidants, and the like.